The present invention relates to spirocyclic cyclohexane derivatives, processes for the preparation thereof, pharmaceutical compositions containing these compounds and the use of spirocyclic cyclohexane derivatives for the preparation of pharmaceutical compositions.
The heptadecapeptide nociceptin is an endogenous ligand of the ORL1 (opioid receptor-like) receptor (Meunier et al., Nature 377, 1995, p. 532-535), which belongs to the family of opioid receptors, is to be found in many regions of the brain and spinal cord, and has a high affinity for the ORL1 receptor. The ORL1 receptor is homologous to the μ, κ and δ opioid receptors and the amino acid sequence of the nociceptin peptide displays a strong similarity to those of the known opioid peptides. The activation of the receptor induced by nociceptin leads via the coupling with Gi/o proteins to an inhibition of the adenylate cyclase (Meunier et al., Nature 377, 1995, p. 532-535).
After intercerebroventicular application, the nociceptin peptide exhibits pronociceptive and hyperalgesic activity in various animal models (Reinscheid et al., Science 270, 1995, p. 792-794). These findings can be explained as an inhibition of stress-induced analgesia (Mogil et al., Neuroscience 75, 1996, p. 333-337). Anxiolytic activity of the nociceptin could also be demonstrated in this connection (Jenck et al., Proc. Natl. Acad. Sci. USA 94, 1997, 14854-14858).
On the other hand, an antinociceptive effect of nociceptin could also be demonstrated in various animal models, in particular after intrathaecal application. Nociceptin has an antinociceptive effect in various pain models, for example in the tail flick test in mice (King et al., Neurosci. Lett., 223, 1997, 113-116). In models of neuropathic pain, an antinociceptive effect of nociceptin could likewise be detected and was particularly beneficial since the effectiveness of nociceptin increases after axotomy of spinal nerves. This contrasts with conventional opioids, the effectiveness of which decreases under these conditions (Abdulla and Smith, J. Neurosci., 18, 1998, p. 9685-9694).
The ORL1 receptor is also involved in the regulation of further physiological and pathophysiological processes. These include inter alia learning and memory (Manabe et al., Nature, 394, 1997, p. 577-581), hearing capacity (Nishi et al., EMBO J., 16, 1997, p. 1858-1864) and numerous further processes. A synopsis by Calo et al. (Br. J. Pharmacol., 129, 2000, 1261-1283) gives an overview of the indications or biological processes in which the ORL1 receptor plays a part or could very probably play a part. Mentioned inter alia are: analgesics, stimulation and regulation of food intake, effect on μ-agonists such as morphine, treatment of withdrawal symptoms, reduction of the addiction potential of opioids, anxiolysis, modulation of motor activity, memory disorders, epilepsy; modulation of neurotransmitter release, in particular of glutamate, serotonin and dopamine, and hence neurodegenerative diseases; influence on the cardiovascular system, triggering of an erection, diuresis, antinatriuresis, electrolyte balance, arterial blood pressure, water retention disorders, intestinal motility (diarrhoea), relaxation of the respiratory tract, micturation reflex (urinary incontinence). The use of agonists and antagonists as anorectics, analgesics (also when coadministered with opioids) or nootropics is also discussed.
The possible uses of compounds that bind to the ORL1 receptor and activate or inhibit it are correspondingly diverse. In addition, however, opioid receptors such as the μ-receptor, but also the other subtypes of these opioid receptors, namely δ and κ, play an important part in the field of pain therapy and also other of the aforementioned indications. It is accordingly beneficial if the compound also has an effect on these opioid receptors.
WO 2004043967 discloses spirocyclic cyclohexane derivatives having a high affinity for the ORL1 receptor but also for the μ-opioid receptor. WO 2004043967 discloses generic compounds wherein R1 and R2 form a ring, but no example compounds having this structural element are disclosed. Only example compounds in which R1 and R2 denote H or CH3 are disclosed, wherein at least one of the radicals R1 and R2 denotes H. These compounds have an exceptionally high affinity for the μ-opioid or ORL1 receptor, as demonstrated by corresponding data.
Metabolic stability is a critical property for the effectiveness of a compound and hence also for the successful development of a pharmaceutical composition. The compounds disclosed as example compounds in WO 2004043967 are broken down in the organism inter alia by N-demethylation. These metabolites are for their part biologically active again.
Active metabolites have to be thoroughly investigated during the development of pharmaceutical compositions. For that reason it is advantageous to develop compounds which form few metabolites.